Easy to open carton



Jan. 29, 1963 H. E. ROTHMANN EASY TO OPEN CARTON 3 Sheets-Sheet 1 FIG. 3

Filed Jan. 30, 1961 FLG. 3A.

FLG. 9.

. 3 smmmmm INVENTOR HARRY E ROTHMAN N ZBY Z ATTORNEYS Jan. 29, 1963 H.E. ROTHMANN 3,075,684

EASY TO OPEN CARTON 3 Sheets-Sheet 2 Filed Jan. 30, 1961 INVENTOR HARRYE.ROTHMANN ATTORNEB Jan. 29, 1963 H. E. ROTHMANN EASY TO OPEN CARTON 3Sheets-Sheet 3 Filed Jan. 30, 1961 N a 0 mm *0! m .N M Hm N m m m //1/\wwm W H A m m a E Y vow \Q R Q? R W m Y B Q\\N ,PN\ x R) WWWEX .MmvHlwn United States Patent 3,075,634 EASY TooPnN eARToN Harry E.Rothmann, Valhalla, N.Y., assignor to General Foods Corporation, WhitePlains, N.Y., a corporation of-Delaware Filed Jan. 30, 1961, Ser. No.85,683 4 Claims. (Cl; 229-51) This invention relates to an easy to opencarton and to a. perforating knife for producing a perforated pattern:on flat carton stock in the form of an arc to prov1de aconvenient andeasy to open aperture inthe finished carton providing ready access tothecontents of the carton.

It is conventional, as in U.S. Patents Nos. 2,865,235 and 2,885,93-3,to.provide cut andfold lines in flat cartonv shaped cuts. in somesuitable-part of the carton blank to.

provide an access opening to the cartonr, Inthese patents the arc-shapedcuts are so disposed as to provide a pouring spout in a narrow side ofthe finished carton.

When an arc-shaped perforated pattern isprovided in one side of a cartonfor easy rupture by the fingers when opening the carton, the-endsof-thearc'may fall adjacent to-a fold line, particular-1ywhen the cartonis small, which unduly weakens the structural strength of the finishedcarton. at the edge of. the carton. where the perforated are is mostsuitably located.

In accordance with the present invention an easy to open carton isprovided having an arc shaped pattern of perforation in a wall of thecarton with the ends of the are adjacent an edge of the finished carton.This perforated pattern preserves the structural strength of thefinished carton at the adjacent edge by so disposing the perforatingknife that the penetration of the central perforating teeth of the knifeare deeper than those at the ends of the knife. The shallowerperforations are adjacent the edge of the carton so that the structuralstrength of the carton at the edge is not appreciably altered, as it isat the center of the arc of perforations. The weakening of the carton atthe central portion of the are where the perforations are deepest ismost advantageous as it is in this area that finger pressure is exertedto open the carton and easy rupture of the carton in this area isdesired.

When carton blanks are formed by passing flat carton stock betweenrotary die rolls, the perforating knife is suitably mounted in the upperroll to act against an anvil provided by the lower roll. The knife isprovided with any suitable number of spaced teeth and the curvature ofthe cutting edge of the knife is intentionally deviated slightly fromthe true radius of the die roll so that the ends of the knife deviatefrom a true radius. The cutting edge of the knife is therefore a curveof constantly varying radius of curvature with the greatest radius ofcurvature at the center of the knife.

In one embodiment of the present concept deviation for the knife fromthe true radius of the die rolls is obtained by grinding the cuttingedge of the knife in the fiat to the true radius of the die roll. Theflat perforating knife is then mounted in the die roll against a surfaceforming an are so that the knife is forced out of a fiat plane into theshape of the arc to be perforated in the carton blank. Bending the knifeout of the fiat into an arc displaces the ends of the knife in thedirection of the radius of the roll so that the knife when brought intocontact with the carton blank perforates the same in an are having theperforations at the ends of the arc shallower than those at the middleof the arc.

The present invention is capable of various structural 3 75,684 PatentedJan. 29, 1963 embodiments one of. which. is. illustrated in theaccompanyingdrawings andis described hereinafter. This illustrative'embodiment should not. be. construed as definingorlimiting theinvention.

In the: accompanying drawings, inwhichlike reference characters indicatelike parts,

FIG. 1 is aschematicview of aweb of fiat carton stock advancing. throughupper andlower die rolls;

FIG. 2 isanenlarged detail of a part of the surface of the upper, die;roll of FIG. 1. showingthe-relative location. of arcuate. perforatingknives of the present invention mounted therein;

FIG. 3 is asectionalview onzthelines 33of FIG. 2;.

FIG. 3a isasectional-viewon-theline 3a-3a of- FIG. 2;

FIG. 4 is atop view ofv the knife mounting clamp shown in FIG. 2; p

FIG. 5 is-a'frontview of the; knife mountingclamp of FIG. 4;

FIG. 6 is a side view of the knife mounting clamp of Fig.4;

FIG. 7 fear schematic view ofthe perforatingknife of FIG; 2to-illustrate-thedisplacement of the ends of the knife when the: knifeisbentfrom-the-flat into. an arc;

FIGL 8is a. carton blank. formedand perforated in accordance with thepresent invention" to the. scale of the: portion of the die roll shownin FIG: 2;,and

FIG. 9 is a cross-sectional view on the line 99. of FIG. 8schematically'showing;the grading of depth of the; perforationsinthe-carton blank in' accordance with the: present concept.

Referring now to the several figures, a web of fiat carton stock it} isadvanced by suitable means between upper male die roll 11 and lowerfemale die roll 12 which are rotated in the direction of the arrowsthereon to bring the pattern mounted on the surface of roll 11 intoengagement with the sheet or web of stock 10 to form carton blanks asshown in FIG. 8. Referring particularly to FIG. 2, the surface of roll11 is provided with any suitable number of patterns across the lengthand around the circum-- ference thereof, in known manner, to form aplurality of carton blanks, as shown in FIG. 8, for each rotation of thedie rolls. Knife edges 13 and 14 are suitably mounted on roll 11 toseparate the carton blank from the web 10 and spaced upstanding blades15, 16, 17 and 18 are disposed along roll 11 to provide spaced foldlines for the carton blank.

With reference to FIG. 8, knives 13 and 14 sever the carton blank fromthe web along edges 19 and 20, respectively, and blades 15, 16., 17 and18 form fold lines 21, 22, 23 and 24, respectively. In like manner foldlines 25 and 26 are formed in the carton blank and cuts 27, 28, 29, 30,31, 32, 33 and 34 are provided to form end tabs and end pieces when thecarton blank is folded into the finished carton. Arc-shaped knives 35are suitably spaced apart and are mounted in the surface of roll 11 toprovide an arc-shaped perforated pattern 36 terminating in fold line 26in a suitable side or wall of the carton.

Knife 35 is mounted against an arc-shaped face 36 of block 37 and isheld in place by the arc-shaped face 38 of block 39 which is secured toblock 37 by bolt 40.

Block 37 is mounted in aperture 41 in roll 10 by bolts 42..

FIGS. 3-6 show the details of construction of the,- knife mounting clampand FIG. 6 shows the displacement; of the ends of the knife in theradius of the die roll to obtain shallower perforations at the ends ofthe areshaped pattern of perforations.

FIG. 7 schematically shows knife 35, here provided with few perforatingteeth 43. Teeth 43 are widely spaced for illustrative purposes only. Itis to be understood that any suitable number of teeth 43, suitablyspaced apart, may be employed to obtained the desired pattern ofperforations as shown at 36 in FIG. 8. Knife 35 has a curved cuttingedge having a radius 44 which is' equal to the radius of male roll 11.When knife 35 is bent out of the fiat into an are between blocks 37andr39 the ends of the cutting edge of the knife move to positions 45and 46 changing the curvature of the cutting edge to a curve ofuniformly decreasing radius from the center of the curve towards theends thereof. The total resulting difference in depth of cut from thecenter of the knife to an end of the knife is shown at 47.

It is therefore apparent, as schematically shown in FIG. 9, that thearc-shaped pattern of perforations 36 will be deeper at the center ofthe arc than at the ends thereof. The perforations will becomeprogressively more shallow as the ends of the arc-shaped pattern ofperforations 36 is approached adjacent fold line 26. The structure ofthe carton is therefore not weakened appreciably at fold line 26 whilereduced finger pressure is required to break the carton beginning at thecenter of the perforated are 36 when the carton is to be opened.

It should now be apparent that the present invention in every waysatisfies the several objectives discussed above.

Changes in or modifications to the above described 4 pattern ofperforations in one carton surface with the ends of said patternadjacent a fold line, said perforations being deeper at the center ofsaid pattern and progressively decreasing in depth from the center ofsaid pattern toward the ends of said pattern.

2. An easy to open carton having at least one fiat surface and anarcuate pattern of perforations in said surface with the ends of thepattern adjacent an edge of said surface, said pattern of perforationsdecreasing in depth from the center toward the ends thereof.

3. In a carton blank having spaced fold lines defining carton surfacesin the finished carton including carton sides and carton end formingflaps, means for easy opening of the finished carton comprising anarc-shaped pattern of perforations in a carton side with the ends ofsaid pattern adjacent a fold line of an end forming flap, saidperforations being deeper at the center of said pattern andprogressively decreasing in depth from the center of said patterntowards the ends of said pattern.

4. An easy to open carton having at least one flat side and an endseparated from the side by a fold edge and an arcuate pattern ofperforations in said side with the ends of the pattern adjacent saidfold edge, said pattern of perforations decreasing in depth from thecenter toillustrative embodiment of the present invention may now 5wards h d th f,

be suggested to those skilled in the art without departing from thepresent inventive concept. Reference should therefore be had to theappended claims to determine the scope of this invention.

What is claimed is:

1. In a carton blank having spaced fold lines defining carton surfacesin the finished carton, means for easy opening of the finished cartoncomprising an arc-shaped References Cited in the file of this patentUNITED STATES PATENTS

1. IN A CARTON BLANK HAVING SPACED FOLD LINES DEFINING CARTON SURFACESIN THE FINISHED CARTON, MEANS FOR EASY OPENING OF THE FINISHED CARTONCOMPRISING AN ARC-SHAPED PATTERN OF PERFORATIONS IN ONE CARTON SURFACEWITH THE ENDS OF SAID PATTERN ADJACENT A FOLD LINE, SAID PERFORATIONSBEING DEEPER AT THE CENTER OF SAID PATTERN AND PROGRESSIVELY DECREASINGIN DEPTH FROM THE CENTER OF SAID PATTERN TOWARD THE ENDS OF SAIDPATTERN.